[TIMOB-12574] iOS: Failed to download specific images for iPad 3 and 4 (Retina)

Although specific suffixes used as default in images' names for iPad and iPhone, it seems to be not always picking up the right file during packaging or deployment on device. Not a regression, occurs in 3.0.0.GA Test steps: 1. Create default project. 2. Replace app.js with the following code

var win = Ti.UI.createWindow({
	backgroundImage:'background.png'
});

win.open();

3. unzip the attachment and add images in to Resources>iphone folder 4. Build the project on device and run it 5. Run in Simulator(Retina) 6. Package, install .ipa file to device and run it Actual result: 4. An image of the car(wrong) 5. An image of the Universe(right) 6. An image of the car(wrong) Expected result: An image of the Universe should be used (background@2x~ipad.png)